The applicant has found that when a liquid detergent product is placed in built-in dispensers of many washing machines, a portion of the product is carried away with the first quantity of the water introduced into the machine, proceeding to the sump and drain lines of the machine. Such portion will remain unutilized and will be discarded fromthe washer with the first operation. This is wasteful of the product and the resulting expense could create an unfavorable reaction on the part of the user respecting liquid detergents. It is therefore desirable to provide a device which will obviate the waste and provide for progressive release of liquid detergent in the wash water.